The objectives of this project are (1) a genetic analysis of meiotic mutants which act in male Drosophila melanogaster and (2) an analysis of the segregational behavior of Y-2 translocations. Two meiotic mutants are currently being examined. One mutant appears to permit nohomologous pairing to occur. Studies with this mutant will be designed to explore the parameters of this nonhomologous pairing. The second mutant acts at the second meiotic division and is chromosone specific. The nature of this specificity will be examined. Experiments will also be conducted to determine whether the mutant also affects mitotic divisions. It has been found that in males, Y-2 translocation heterozygotes have a particular pattern of chromosone segregation, in that certain expected gametic classes are missing. Experiments to further explore the nature of the disjunctional types found in males are planned. These will include crosses which will determine the effect of other types of aberrations on translocation segregation. BIBLIOGRAPHIC REFERENCES: Gethmann, Richard C. 1976 Meiosis in male Drosophila melanogaster II. Nonrandom segregation of a compound-2 chromosone. Genetics, in press. Gethmann, Richard C. 1974. Meiosis in male Drosophila melanogaster I. Isolation and characterization of meiotic mutants affecting second chromosome disjunction. Genetics 78: 1127-1142.